That is an enormous question. There are so many ways. Are you interested in one particular area? Clothing, food, music, art, worship practices, poetry, military practices, sciences, architecture, and the list could go on and on and on.

I don't know if my answer is in anyway extensive enough for this subreddit, so feel free to correct me if need be.

Looking at religion, Sikhism does seem to be (atleast to som extent) a mix of Hindu and muslim beliefs and teachings. For instance they do not eat halal food. The Sikh teachings also focus on equality for humans and selfless acts, much like we see in Islam. It is also regarded as a monoteistic religion, whereas hinduism is very polyteistic. In Sikh temples, however, there is often shrines dedicated to several Hindu deities too. Sikhism was developed in the Punjab region of India while it was being ruled by the Mughal empire, which was a muslim empire, while India was dominantly Hindu. This naturally resulted in a very syncretic religion, combining different aspects of both Hinduism and Islam. It is important to note that Sikhs do not regard the religion as a mix of Islam and Hinduism and it may not be, it is however easy to find similarities between the two. This is just information as I remember it and since Im a work right now I don't really have time to find sources on this right now, sorry. I am however certain that there are people in here who are way more capable of answering your questions.